Protocol examples updated to use Structs

lib/koans/16_protocols.ex

@@ -0,0 +1,50 @@
+defmodule Protocols do
+  use Koans
+
+  defprotocol School do
+    def enrol(person)
+  end
+
+  defmodule Student do
+    defstruct name: ""
+  end
+
+  defmodule Dancer do
+    defstruct name: "", dance_style: ""
+  end
+
+  defmodule Baker do
+    defstruct name: ""
+  end
+
+  defimpl School, for: Student do
+    def enrol(student) do
+      "#{student.name} enrolled at secondary school"
+    end
+  end
+
+  defimpl School, for: Dancer do
+    def enrol(dancer) do
+      "#{dancer.name} enrolled for #{dancer.dance_style}"
+    end
+  end
+
+  defmodule EveningSchool do end
+
+  koan "Sharing an interface is the secret at school" do
+    student = %Student{name: "Emily"}
+    assert School.enrol(student) == ___
+  end
+
+  koan "Dancers share but belong to a different school" do
+    dancer = %Dancer{name: "Darcy", dance_style: "ballet"}
+    assert School.enrol(dancer) == ___
+
+  end
+
+  koan "If you don't comply you can't get in" do
+    assert_raise ___, fn ->
+      School.enrol(%Baker{name: "Delia"})
+    end
+  end
+end

lib/runner.ex

@@ -15,6 +15,7 @@ defmodule Runner do
     Processes,
     Tasks,
     Agents,
+    Protocols,
   ]
 
   def koan?(koan), do: Enum.member?(@modules, koan)

mix.lock

@@ -1,2 +1,2 @@
-%{"exfswatch": {:hex, :exfswatch, "0.1.1"},
-  "fs": {:hex, :fs, "0.9.2"}}
+%{"exfswatch": {:hex, :exfswatch, "0.1.1", "7ccf6fc9b443d04dada3e50b21f910b4d0e4546ce7772dc6d4181fb929ea186f", [:mix], [{:fs, "~> 0.9", [hex: :fs, optional: false]}]},
+  "fs": {:hex, :fs, "0.9.2", "ed17036c26c3f70ac49781ed9220a50c36775c6ca2cf8182d123b6566e49ec59", [:rebar], []}}

test/koans/protocols_koans_test.exs

@@ -0,0 +1,14 @@
+defmodule ProtocolsTests do
+  use ExUnit.Case
+  import TestHarness
+
+  test "Protocols" do
+    answers = [
+      "Emily enrolled at secondary school",
+      "Darcy enrolled for ballet",
+      Protocol.UndefinedError
+    ]
+
+    test_all(Protocols, answers)
+  end
+end